1. Field of the Invention
The present invention relates to a semiconductor device particularly favorable for thinning thereof and a method of producing the same.
2. Description of Related Art
A typical step of assembling a semiconductor device involves the steps of dicing a semiconductor wafer to produce individual semiconductor chips, die-bonding the semiconductor chip to a lead frame, wire-bonding a pad of the semiconductor chip and the lead frame, and resin-molding a lead in a state where it is pulled out to the outside.
In order to thin the whole of the semiconductor device, the semiconductor chip itself must be thinned. Therefore, prior to dicing the semiconductor wafer, a grinding step for grinding an inactive surface (a back surface) of the wafer using a grinder is carried out. The wafer which has been thinned to a predetermined thickness is then diced, so that individual semiconductor chips are cut out.
When the thin semiconductor wafer is divided by a dicing saw, however, the wafer is cracked, and the chip is chipped. Therefore, the thinning of the wafer before the dicing has a limit.
In recent years, a method of first dicing the water and then, grinding the back surface of the wafer has been proposed. Specifically, an inactive surface 102 of a wafer 100 is bonded to a dicing tape 105 in a state where an active surface 101 of the wafer 100 is exposed, as shown in FIG. 9A. In this state, a half-cut step for providing the wafer 100 with cutting grooves 103 to a depth of approximately 50 μm from the active surface 101 is carried out using a dicing saw 107. Subsequently to the half-cut step, the dicing tape 105 on the inactive surface 102 is stripped, and a dicing tape 106 is affixed to the active surface 101, as shown in FIG. 9B. In this state, the grinding of the inactive surface 102, that is, back surface grinding is performed using a grinder 109. The back surface grinding is performed until the inactive surface 102 reaches the cutting grooves 103. When the cutting grooves 103 appear by the back surface grinding, individual semiconductor chips 110 having a thickness of approximately 50 μm are obtained (FIG. 9C).
The semiconductor chips 110 which have been thinned can be thus produced without cracking or chipping at the time of dicing.
The semiconductor chips thus produced are thereafter carried on a mounting board. Further, a semiconductor device (an integrated circuit device) is completed through steps such as connection of an external terminal and resin molding.
However, the semiconductor chips 110 which have been thinned may be cracked or chipped at the time of handling. For example, the semiconductor chips 110 are carried on the mounting board automatically by a robot. The thin semiconductor chips 110 are cracked or the corners thereof are easily chipped by an external force applied when they are held by the hands of the robot.
Consequently, the above-mentioned prior art can prevent chips from being cracked or chipped at the time of dicing, while causing a new problem such as cracking or chipping at the time of handling.